Evaporative cooling systems are used to cool spaces by distributing water over a media filter and drawing air through the media filter with a blower so as to lower the temperature of the air as the water evaporates. It has been proposed in the past to employ roof-mounted evaporative cooling systems for large motor vehicles, such as, buses as an efficient means of lowering the temperature of the passenger area. One approach taken in the past has been to employ a pair of housings in side-by-side relation, each housing containing a series of blowers mounted in tandem, a filter block extending lengthwise and in closely-spaced parallel relation to the blowers, and a diffuser for discharging water from a circulating tank into the filter block. Each filter block soaks up water from the diffuser and spreads the water uniformly throughout so that the air, when drawn across the filter block, will pick up moisture and cool the air preliminary to discharge through downwardly directed ducts extending from the discharge or exhaust sides of the blowers into the interior of the bus.
Numerous problems have been encountered in roof-mounted evaporative cooling systems of the type described: The cooled air was directed downwardly through the center of the bus or to the outside but still in a substantially vertical direction and did not afford even circulation; the blowers were mounted in a housing which in turn was directly bolted into the roof of the bus creating severe leakage problems as well as problems of vibration and noise transmitted by the blowers through the roof of the bus; the internal reinforcing of the filter block and blower were insufficient to overcome the vibration and noise problem and there was a tendency for the excess water which seeped out from the filter block to be splashed back toward the center or blower section, for example, when the bus negotiated a turn or curve. Other problems were experienced with the relative difficulty of removal of the filter blocks for cleaning purposes.
Representative of approaches taken in the past are disclosed in U.S. Pat. Nos. 2,784,568 to H. O. Schjolin; 2,404,961 to G. C. Hoch; 4,186,546 to M. Myers; and 4,201,064 to Martin Krug et al; as well as the Operator's Manual for Sutrak Evaporative Cooling System for RTD Buses, (Raymond, David L.) and the publication entitled "Transit.multidot.Aire" (Norsaire Corporation, 1983).